Maine adds muscle to battle against invasive crab

  • Mail this page!
  • Delicious
  • 0

FREEPORT — The green crab population along Maine’s coast has exploded in recent years, with the invasive species devouring acres of once-healthy clam flats.

The only organized effort aimed at understanding, and potentially thwarting the demise of the state’s third largest fishery, has until now been a collaboration between Freeport clammers and the town.

The state, along with most commercial clammers, had all but dismissed the issue – at least until this summer.

Attitudes of clammers and the state have now shifted, with the industry and the state making the green crab a major priority.

Last week, the state Department of Marine Resources launched the first public, statewide effort aimed at understanding the effect of the invasive crab species. This comes more than a year after Freeport clammers first received town support to look into how the explosion of green crabs had severely crippled historically productive clam flats.

The state event, a one-day trapping effort that included 30 towns from Ogunquit to Lubec, was intended to not only gather data, but also put green crabs on the map as a major threat to the clam population, said Kohl Kanwit, public health bureau director at DMR.

“This is one thing DMR could do that no one else could. It’s a pretty unique effort to have both ends of the coast involved,” Kanwit said. “We hope to use this data as a coast-wide snapshot.”

Kanwit said the data is now being compiled and is expected to be available within the next couple of weeks.

The data will help paint a picture of where the crabs are most concentrated. But because trapping techniques, trap types and length of time in the water varied, the study is anything but strictly scientific.

Still, Kanwit said the survey will be useful in not only getting a general sense of how large the problem is, but also in educating clammers who have been resistant to accepting the predator as a major problem.

“It just seemed ridiculous,” she said of the attitude toward Freeport clammers’ claims about green crabs being responsible for the clam decline. “But now people are seeing what’s happening and they’re like, hah, this is not ridiculous anymore.”

Waldoboro clammer Glen Melvin, who participated in the survey and hauled in two, five-gallon buckets of green crabs in the 24-hour period, said although clams in his area have taken a major hit in recent years, he remains hesitant to pin it all on green crabs. 

“I have been a skeptic since it began,” he said, noting that he originally thought the nearly microscopic juvenile clams were too small for the crabs to eat.

But, with a major increase of green crabs in his area, Melvin said it’s hard to deny. 

“We’re not sure if it’s the actual issue, but there’s no seed, no small clams, no future generations,” he said. “All we have is large clams.”

He hopes this effort by DMR will be the first of many.

“This is the beginning of what we need to do to attack the problem and get more data and learn where these things come from,” Melvin said. “This is the beginning of a solution, hopefully.”

Historically, when the crabs’ population spiked, they were killed off by long, cold winters. But because of the mild winters and warming water temperatures in the last couple decades, their numbers have swelled.

A similar warm period occured in the 1950s, allowing the crabs to destroy productive flats. But during the 1960s, Maine endured severe winters that essentially knocked back the crab population to where it was no longer a threat.

Researchers now fear that warm temperatures are part of a new normal and that Maine is not likely to see the similar harsh, extended winters of the past.

And state officials have taken notice.

In addition to the statewide survey, DMR also created a special page dedicated to green crabs on the state website.

The page, which launched in July, provides an overview of efforts to address the issue, such as developing a market for them, targeted trapping and fencing initiatives, and public outreach.

Despite the state’s new focus on the issue, Kanwit said DMR has not dedicated any additional money to fund studies or abatement work.

Instead, researchers like Brian Beal, a biologist and professor at the University of Maine at Machias who has studied green crabs since the 1980s, are helping lead the effort.

Beal and clammers in Freeport are working on a nearly $70,000 town-funded project that focuses on aggressively trapping the crabs and fencing off sections of the Harraseeket River to keep them out. It also will study the impact of other environmental factors believed to contribute to clam population decline, such as ocean acidification.

Brunswick clammers are also trapping, but more modestly, said Dan Devereaux, the town’s marine resource police officer.

Devereaux is coordinating the trapping efforts with the town’s marine resources committee and said about 20 clammers are fishing green crab traps, weighing their catch and recording the data.

The Town Council has yet to formally discuss funding a large project, he said, adding that a project similar to Freeport’s might be considered if it proves successful.

Kanwit said the town of Penobscot has been making similar efforts. Their once-commercially productive flat in Northern Bay is now empty after green crabs and another predator, moon snails, ate through all the clams.

The state has issued the town special permits for experimental trapping and fencing, she said, in an effort to try to restore the resource.

Universities are playing additional roles, too. While Beal is the leading scientist, other researchers at the University of Maine are working on building more effective traps and constructing economic models to develop viable markets to sell the crabs, Kanwit said.

The crabs have proved hard to sell as food, because they produce little meat, are hard to crack open, and are not as flavorful as other crabs.

Along with the research, this fall the state is collaborating with the University of Maine Sea Grant Program to host a symposium on green crabs. The conference is expected to attract researchers from around the country.

Maine’s two U.S. senators have also taken an interest in the crabs. In a July endorsement of a $6 million National Science Foundation grant for three-year study of the many factors affecting the health of Maine and New Hampshire’s shared coastal ecosystem, Sens. Angus King and Susan Collins specifically cited the threat green crabs pose to the clamming industry.

Although DMR has only now started to push a campaign, it has been meeting with the Maine Clammers Association since April to talk about the problem posed by green crabs.

The MCA, led by vocal Freeport clammer Chad Coffin, has been calling attention to the issue for the last couple of years and has made strides with the state and clammers. 

Coffin said the issue of green crabs has often alienated fishermen from each other, because it bucked conventional wisdom.

“Over-fishing, we’ve always been taught, is the problem in the shellfish and lobster industries,” he said. “But it’s not a matter of over-fishing. The biggest thing we’ve discovered is that we’re not the ones who’ve been fishing out all the resources. It’s the crabs.”

And while clams have up to this point been the main course for the crabs, researchers now worry the crabs may move onto the state’s prized fishery, lobster, although no research efforts have been launched to determine if this happening.

Recently, scientists and clammers have noticed another worrying trend thought to be caused by green crabs: the erosion the ecologically vital eelgrass.

The crabs nest beneath the grass, clipping its roots and killing it, something that could have serious implications for a wide array of wildlife, according to Hilary Neckles, a research ecologist with the U.S. Geological Survey.

Neckles is conducting research on eelgrass devastation in Maquoit Bay, near Little Flying Point in Freeport.

She said the area used to have 500 hectares of eelgrass that extended from the intertidal zone to the central channel. Now the majority of it has all but vanished.

The plant, which is rooted, unlike seaweed, acts as a nesting, feeding and refuge area for juvenile lobsters, mussels and birds. It also acts sucks up large amounts of nutrients, making it essential for preservation of the ecosystem’s water quality.

The primary loss in the Maquoit Bay, Neckles said, happened between 2011 and 2012, although the scientific community only became aware of the loss this year.

“We started looking and it was like, wow, this entire meadow has almost disappeared,” she said, noting that people she has spoken with saw chunks of eelgrass the size of a barn floating in the bay. “It’s really depressing.”

Neckles said her study will not prove green crabs are the cause without a doubt, but that it “certainly points to green crabs for being the causal agent for the decline.”

Similar devastation of eelgrass has happened in Nova Scotia, she said, noting that whole bays were destroyed by green crabs.

“The ramifications of losing eelgrass are tremendous,” Neckles said. “We would expect to see major reduction in the fish and wildlife population.”

Will Graff can be reached at 781-3661 ext. 123 or Follow him on Twitter: @W_C_Graff

Sidebar Elements

A container full of green crabs caught in July in the Harraseeket River in Freeport.

The juvenile soft-shell clam, shown here, is a favorite target of green crabs.